1. Field
The present specification generally relates to coating apparatus and methods and, more particularly to apparatus and methods for coating monolith substrates with coating layers.
2. Technical Background
Porous inorganic membranes have been commercialized for years in industrial liquid filtration separations, and have recently been investigated for gas separation and catalytic reactions. Most recently, they have been explored for gas-particulate separation in diesel particulate filter (DPF) and gasoline particulate filter (GPF) applications, and vapor-vapor separation in on-board separation of gasoline (OBS) applications. For applications such as these, the inorganic membranes may be applied to porous or dense monolith substrates using a variety of coating processes, including dip-coating, slip-casting and spin-coating. Scalability of such processes often depends on amenability of the processes to accommodate various shapes and sizes of monolith substrates. Variances in shapes and sizes among monolith substrates can further complicate apparatus scalability, particularly when the monolith substrates require a centrifugal spin step to remove excess liquid from the channels after being coated.
Accordingly, ongoing needs exist for scalable coating apparatus and methods for coating monolith substrates with coating layers, including but not limited to inorganic membranes.